- A general asymmetric route to enantio-enriched isoflavanes via an organocatalytic annulation of o-quinone methides and aldehydes
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Reported herein is a general approach to optically active isoflavanes based on a chiral amine-catalyzed [4 + 2] asymmetric annulation of o-quinone methides and aldehydes. A number of naturally occurring isoflavanes, including equol, sativan, isosativan, v
- Zhang, Jian,Zhang, Shuangzhan,Yang, Huixin,Zhou, Ding,Yu, Xueting,Wang, Wei,Xie, Hexin
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supporting information
p. 2407 - 2411
(2018/05/24)
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- Synthetic access to optically active isoflavans by using allylic substitution
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A general approach to the (S)- and (R)-isoflavans was invented, and efficiency of the method was demonstrated by the synthesis of (S)-equol ((S)-3), (R)-sativan ((R)-4), and (R)-vestitol ((R)-5). The key step is the allylic substitution of (S)-6a (Ar1=2,4-(MeO)2C6H3) and (R)-6b (Ar1=2,4-(BnO)2C6H3) with copper reagents derived from CuBr·Me2S and Ar2-MgBr (7a, Ar2=4-MeOC6H4; 7b, 2,4-(MeO)2C6H3; 7c, 2-MOMO-4-MeOC6H3), furnishing anti SN2′ products (R)-8a and (S)-8b,c with 93-97% chirality transfer in 60-75% yields. The olefinic part of the products was oxidatively cleaved and the Me and Bn groups on the Ar1 moieties was then removed. Finally, phenol bromide 9a and phenol alcohols 9b,c underwent cyclization with K2CO3 and the Mitsunobu reagent to afford (S)-3 and (R)-4 and -5, respectively.
- Takashima, Yuji,Kaneko, Yuki,Kobayashi, Yuichi
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experimental part
p. 197 - 207
(2010/03/03)
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- Oligomeric isoflavonoids. Part 4. Synthesis of the daljanelin class of isoflavonoid-neoflavonoid dimers
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A protocol of introducing an electrophilic C1 fragment to a pterocarpan nucleus, followed by anionic coupling of a C6-C2 benzofuranoid precursor and late introduction of the final C6 fragment, permitted the synt
- Rohwer, Mark B.,Van Heerden, Pieter S.,Brandt, E. Vincent,Bezuidenhoudt, Barend C. B.,Ferreira, Daneel
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p. 3367 - 3374
(2007/10/03)
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- Synthesis of Isoflavanoid Oligomers Using a Pterocarpan as Inceptive Electrophile
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(3S)-2',7-Dihydroxy-4'-methoxyisoflavan serves as bifunctional nucleophile at C-5' and C-6, when condensed with the carbocation generated at C-11a of its (6aS,11aS)-3-hydroxy-9-methoxypterocarpan analogue under mild acid conditions or by photolysis, to fo
- Bezuidenhoudt, Barend C. B.,Brandt, Edward V.,Roux, David G.
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p. 2767 - 2778
(2007/10/02)
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